1. Field of the Invention
This invention relates to collets for tube couplings which receive and automatically grip and hold a tube inserted in the coupling.
2. Background Prior Art
More particularly the invention relates to collets for tube couplings of the kind having a body formed with a throughway open at one end and having a encircling cam surface tapering towards said open end with a cylindrical collet located in the open end of the throughway and projecting into the throughway to receive a tube, the collet being formed with flexible arcuate section arms having projecting teeth on their inner surfaces to engage the tube and engageable on their outer surfaces with the tapered cam surface so that outward movement of the collet causes the arms to be pressed inwardly to grip and hold the tube in the bore. Hence, a pull on the tube, causes the collet arms to be pressed into tighter engagement with the tube. The tube may be released from such a coupling by pressing or holding the collet axially inwardly of the coupling body whilst the tube is withdrawn. Examples of said tube couplings are described and illustrated in my U.K. Patent No. 1520742, U.K. Patent No. 1573757 and U.K. Patent No. 2132296.
My U.K. Patent No. 1573757 discloses a particular form of collet in which the inner surface of the radially flexible arm of the collet is formed with an inwardly projecting tooth to engage and grip the tube inserted through the collet. The projecting tooth enhances the grip of the arm with the tube and it is an object of the present invention to further enhance the grip which the arm can apply to the tube.